In recent years, there is a stronger demand for an increase in communication speed of radio communication. As one of methods responding to such a request, there is a method of increasing a frequency bandwidth of a radio channel used for radio communication. On the other hand, a radio frequency band is a precious resource used for various applications and is required to be effectively utilized.
In view of such a situation, it is desirable to further allocate a frequency band, which is already used as another application, as a radio channel, realize coexistence with an existing radio technique, and improve efficiency of use of a frequency band as a precious resource. As a method of increasing a frequency bandwidth of a radio channel while improving efficiency of use of a frequency band in this way, a technique for performing radio communication regarding plural radio channels as a radio channel in a wide bandwidth by simultaneously using the plural radio channels is effective.
For example, in the communication standard IEEE802.11n of the next-generation radio LAN, there is proposed a technique for realizing high-speed radio communication regarding two radio channels in 20 MHz width as a radio channel in 40 MHz width by simultaneously using the radio channels.
However, there is a harmful effect in proceeding with such measures to aim at realization of higher-speed radio communication as a radio channel in a wide bandwidth simultaneously using plural radio channels.
For example, JP-A 2005-301591 (Kokai) discloses a technique with which, in a radio communication channel that performs radio communication using plural radio channels, each of radio communication apparatuses performs carrier sense for the plural radio channels and performs radio communication simultaneously using plural radio channels judged as not being used.
In the technique disclosed in JP-A 2005-301591 (Kokai), each of the radio communication apparatuses secures the radio channels, which are judged as not being used as a result of the carrier sense, one by one and, at a stage when the number of radio channels used for radio communication is secured, performs radio communication simultaneously using the plural radio channels.